1. Field of the Invention
The present invention generally relates to building construction, and more particularly to an apparatus for aiding in the fabrication of metal framed walls and trusses for commercial and residential buildings.
2. Description of Prior Art
Metal framed walls and roof trusses have been in use for many years primarily in commercial buildings, and are now becoming popular for residential homes due to the increasing cost and declining quality of lumber, and also the reduced fire danger provided by metal framing. Although building metal frame sections, i.e., metal framed walls and trusses, can be manually constructed on the job site, it is somewhat difficult since both sides of the wall or truss at the top and at the bottom plates or cords must be affixed with metal holding screws on each of the oppositely disposed sides, and this involves turning the entire wall or truss over to gain access to the second side after the holding screws have been applied to the front side, and this due to the fact most walls and trusses are constructed laying flat on a flat surface. This flipping of the wall sections and trusses is time consuming and requires labor. Additionally, since the wall or truss is not completing and securely screwed together at the point in time when inverting is required to access the second side thereof, racking and flexing can occur leading to a decrease in the overall accuracy of the completed metal framed section.
The most commonly used metal building structural members, i.e., studs, cripple studs, trimmers, headers, top and bottom plates, joists, rafters, truss cords and webs and the like are most often created out of various lengths of commercially available thin C shaped metal channels (thin channel iron) normally readily available in gauges between 12 and 25 for conventional building framing, and most commonly made of galvanized or rust resistant roll-formed steel. The metal members are usually structured 15/8 inch in width across the face, and 35/8 inch in depth to simulate the size of a traditional planed wood 2.times.4 in order to be compatible with conventional building plans. Such metal building structural members are also available in sizes simulating or compatible with most nominal planed construction lumber sizes such as 2.times.6, 2.times.8, 2.times.10 and so on. The metal building structural members are available in many pre-cut lengths, such as 8 or 9 foot lengths for placing the members (studs) vertically for defining walls and determining ceiling heights, and in much longer lengths, such as 20 to 40 feet for use as top and bottom walls plates, floor and ceiling joists, rafters, webbings, braces and the like. Such long members are also used for unusually tall walls.
The C channel most commonly used in conventional metal framing is sufficiently flexible due to the thinness of the material to allow the full insertion of a terminal end of one member into the open "C" of a second member, wherein the narrow side walls of the two members overlap at perpendicular angles, or as is common with truss members at obtuse or acute angles, and it is at this overlap of the narrow side walls that holding screws are applied to secure the members to one another.
It can be more economical to use prefabricated metal wall sections and roof trusses which have been fabricated in an efficient factory style setting elsewhere and delivered to the job site. Providing prefabricated wall sections and trusses can result in substantial cost savings by decreasing the amount of time and labor performed on the job site. Recognition of the possibility of such cost savings has led to production of wood framed walls (and trusses) using semi-automated machinery at remote sites, with the wooden wall sections or trusses being shipped to the building site. One such device is described in U.S. Pat. No. 4,876,787 for an apparatus and method for frame wall fabrication. The patent was issued to Ditty et al on Oct. 31, 1989. The Ditty et al apparatus fabricates frame walls from wooden end plates and studs, and includes registration of wooden members for end plates and for studs. An automatic nailer tacks the end plates and studs together one at a time until the desired wall length is achieved. A staking and anchoring mechanism presses the plates and studs together so as to rigidity the frame wall. The operations of the apparatus are controlled by a micro-processor controller which can be re-programmed for various types of walls.
Another process for fabricating walls is described in U.S. Pat. No. 3,851,384, which was issued to Kellner et al on Dec. 3, 1974. The Kellner et al device describes a process for fabricating walls from wood framing materials of the type normally used in constructing frame buildings. The process includes a series of sequentially actuated machine systems electrically interconnected for selecting and feeding components and for selectively assembling the components into walls having adjustably regulated dimensions including openings defining doors and windows. The wooden components are fed into the system and are selectively indexed in response to a series of machine control signals derived from a source of intelligence, such as a coded tape. The wooden components are then automatically nailed together as the wall unit is fed through the machine system.
R. F. Wright was issued U.S. Pat. No. 4,295,269 for a truss assembly apparatus on Oct. 20, 1981. Wright's apparatus includes an elongated table with a movable presser carriage for embedding fastener plates into precut wooden truss members positioned on the table. Clamping assemblies are mounted to the table for securing the truss members securely.
R. C. Wright was issued U.S. Pat. No. 3,897,620 on Aug. 5, 1975 for a method and means for making a wall section. This invention includes a substantially automatic assembly line type operation having a wall support with a carriage having a jig apparatus thereon movable through a plurality of machines for inserting wooden members in the jig apparatus, securing the members together, placing sheeting material on the members, and securing them to another machine for placing windows in the wall section.
A pressure actuated clamp for truss manufacturing equipment is described in U.S. Pat. No. 4,660,815, issued to Rosser on Apr. 28, 1987. The Rosser device includes a clamping apparatus for securing wooden chord and web members together for manufacturing wooden trusses. The clamping apparatus includes an inflatable conduit to force and elongated clamp into a closed position for securing the wooden members in place. The apparatus includes a jig table, with inflatable conduit, and a movable presser carriage for pressing metal toothed plates into the truss members.
Unfortunately, the same mass production machinery used for fabricating wooden stud frame walls and trusses is not well suited for metal framed walls and roof trusses. The wood frame wall fabricating assemblies previously mentioned all either shoot nails through the top and bottom plates and into the terminal ends of the studs or press nail plates into the joints of the wall, neither of which would work for metal structural frame members which are elongated and C shaped in cross section, and made of thin metal. Currently most building codes require metal studs to be joined to the metal top and bottom plates with metal holding screws placed two to each side of the wall or trusses, one screw to the top plate, one on the bottom plate, and this on each oppositely disposed side of the plates or wall section. This holding screw or fastener pattern is also normally applicable to window and door headers and sills, truss cords and webs, and cripple studs and the like. Once the first side holding screws are applied, holding screws must be applied to the second side, and this is a problem existing in the industry which is costing time and thus money. Often the application of the second side holding screws requires inverting the wall section or truss to affix the screws, since most of the time the walls and trusses are constructed laying down or flat on a surface for improved accuracy in layout, safety and generally greater ease in the process. Another problem existing in the building of metal framed walls and trusses is that the ends of the studs, webs and other members which are supposed to be tightly abutted against one another are not being consistently tightly abutted prior to the application of the holding screws, and this results in the very undesirable condition of the wall or truss not being even or straight, and also the fasteners being relied upon to attempt to support the vertical weight or other loading of the structure, as opposed to the members abutting tightly against one another wherein the screws generally simply prevent lateral displacement of the structural members relative to one another.